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From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, Hamza Mahfooz <someguy@effective-light.com>
Subject: Re: [PATCH 0/5] const-correctness in grep.c
Date: Wed, 22 Sep 2021 11:57:57 -0700	[thread overview]
Message-ID: <xmqqlf3o780a.fsf@gitster.g> (raw)
In-Reply-To: <YUlVZk1xXulAqdef@coredump.intra.peff.net> (Jeff King's message of "Mon, 20 Sep 2021 23:45:42 -0400")

Jeff King <peff@peff.net> writes:

> While discussing [1], I noticed that the grep code mostly takes
> non-const buffers, even though it is conceptually a read-only operation
> to search in them. The culprit is a handful of spots that temporarily
> tie off NUL-terminated strings by overwriting a byte of the buffer and
> then restoring it. But I think we no longer need to do so these days,
> now that we have a regexec_buf() that can take a ptr/size pair.

Yes, the haystack has not been read-only exactly because we didn't
have <ptr,size> based regexec variant when the grep machinery was
written, and there is no reason why we want to use the "temporarily
terminate by swapping the byte with a NUL" trick.

It always is a pleasure to read such a concise and to-the-point
summary.  With a clear summary like that, a reader almost does not
have to see the patch to guess how the rest of the story goes ;-)

      parent reply	other threads:[~2021-09-22 18:58 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-21  3:45 [PATCH 0/5] const-correctness in grep.c Jeff King
2021-09-21  3:46 ` [PATCH 1/5] grep: stop modifying buffer in strip_timestamp Jeff King
2021-09-21  5:18   ` Carlo Arenas
2021-09-21  5:24     ` Eric Sunshine
2021-09-21  5:40       ` Carlo Arenas
2021-09-21  5:43       ` Jeff King
2021-09-21  6:42         ` Carlo Marcelo Arenas Belón
2021-09-21  7:37           ` René Scharfe
2021-09-21 14:24             ` Jeff King
2021-09-21 21:02               ` Ævar Arnfjörð Bjarmason
2021-09-22 20:20                 ` Jeff King
2021-09-23  0:53                   ` Ævar Arnfjörð Bjarmason
2021-09-21  3:48 ` [PATCH 2/5] grep: stop modifying buffer in show_line() Jeff King
2021-09-21  4:22   ` Taylor Blau
2021-09-21  4:42     ` Jeff King
2021-09-21  4:45       ` Taylor Blau
2021-09-21  3:48 ` [PATCH 3/5] grep: stop modifying buffer in grep_source_1() Jeff King
2021-09-21  3:49 ` [PATCH 4/5] grep: mark "haystack" buffers as const Jeff King
2021-09-21 12:04   ` Ævar Arnfjörð Bjarmason
2021-09-21 14:27     ` Jeff King
2021-09-21  3:51 ` [PATCH 5/5] grep: store grep_source buffer " Jeff King
2021-09-21  4:30 ` [PATCH 0/5] const-correctness in grep.c Taylor Blau
2021-09-21 12:07 ` Ævar Arnfjörð Bjarmason
2021-09-21 14:49   ` Jeff King
2021-09-21 12:45 ` [PATCH 6/5] grep.c: mark eol/bol and derived as "const char * const" Ævar Arnfjörð Bjarmason
2021-09-21 14:53   ` Jeff King
2021-09-21 15:17     ` Ævar Arnfjörð Bjarmason
2021-09-21 19:18       ` Jeff King
2021-09-23 13:56         ` Ævar Arnfjörð Bjarmason
2021-09-24  4:22           ` Junio C Hamano
2021-09-22 19:02     ` Junio C Hamano
2021-09-22 18:57 ` Junio C Hamano [this message]

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